There is an ongoing academic debate about the question whether sub-state nationalist parties should be considered as niche parties, focusing almost exclusively on their core issue of centre-periphery relations, or whether their electoral appeal can be considered as multidimensional. In that case, these other dimensions can vary with regard to the specific ideological position, historical circumstances and strategic considerations. In this article, we address this theoretical question by relying on the case study of the substate nationalist parties in the Flemish region of Belgium, where they jointly obtained 44% of the vote in the most recent elections. Comparing election surveys from 2009, 2014 and 2019 suggests that the electoral appeal of these parties rests on a mixture of nationalist issues, right-wing economic policies and a restrictive attitude towards immigration. These results suggest that sub-state nationalist parties are not purely niche parties, but should be seen as multiple issue parties, and this broader electoral appeal can explain the discrepancy between electoral results and public opinion on the core issues of these parties.